1. Field of the Invention
The present invention relates generally to data processing systems and in particular, the present invention relates to a method, apparatus and computer program product for querying data in a database. Still more particularly, the present invention relates to a method, apparatus, and computer program product for querying data and an associated ontology in a database management system.
2. Description of the Related Art
The term “data” generally refers to information that is highly structured and has fixed relationships between the different pieces of information, called the data elements. A set of data elements that are logically related may be stored in a systematic way as a collection of records in a computer, called a database. The logical relationships between the data elements allow the database to be queried and information extracted from the database. By querying the database, a user can extract meaningful information about the data elements. The computer program used to manage and query a database is known as a database management system (DBMS).
The database management system manages the data based on the relationships between the data elements. A database management system manages the data by providing a way to perform various operations to the data elements. The operations that may be performed to the data elements in a database include adding data elements, removing data elements, modifying data elements, sorting data elements, and querying the data elements. A database query typically contains one or more logical rules. In processing a query, the database management system extracts from the database all the data elements which match the logical rules in the query.
The term “ontology” generally refers to knowledge about the data elements. A given set of data elements may have one or more associated ontologies. An ontology has characteristics that do not make it suitable for storage in a database. For example, the knowledge in an ontology is typically less structured than the data elements. Therefore, an ontology is typically not stored or managed by a database management system.
Currently, users can query data elements in a database using a database management system. However, users cannot query the ontology associated with the data elements in the same way because the ontology is not suited for being stored in a database. Users also cannot query the data elements and the ontology together to infer new knowledge.
Because the ontology contains valuable information about the data elements, if the data elements and ontology could be linked and managed together, users could then formulate queries to infer new knowledge based on the data elements and the ontology.